a) Field of the Invention
The present invention relates to a vehicle pedal power saving mechanism for a pedal-driven vehicle, and more particularly to such a vehicle pedal power saving mechanism which uses a gear set and a piston unit to change a rotary motion to a linear motion, causing a spring to alternatively reserve energy and release reserved energy, so as to facilitate pedaling of the pedal cranks of the vehicle.
(b) Description of the Prior Art
The pedal transmission mechanism of a pedal-driven vehicle for example a bicycle, generally comprises an axle, two pedal cranks connected to two opposite ends of the axle, a chain wheel mounted on the axle and turned with the axle when the pedal cranks are pedaled, a rear hub sprocket mounted on the rear hub of the rear wheel, and a chain coupled between the chain wheel and the rear hub sprocket. When the pedal cranks are pedaled by legs, the chain wheel is rotated with the axle, thereby causing the rear hub sprocket to be driven by the chain to rotate the rear wheel of the bicycle. When pedaling the crank pedals through 360.degree., the pedal cranks cannot positively receive applied force from the legs of the rider at a particular angle. As illustrated in FIG. 1, a complete rotary stroke of the pedal cranks is divided into four segments. When at the segment A, the pedal crank 10 or 20 can easily be pushed forwards with less effort. However, when at the segment B or the segment D, the rider must applied much effort to push the pedal crank 10 or 20 forwards. Because much effort must be applied to the pedal crank 10 or 20 when at the segment B or the segment D, it is difficult to keep the rear wheel of the bicycle to be rotated at a constant speed.